> For the complete documentation index, see [llms.txt](https://boxlang.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://boxlang.ortusbooks.com/boxlang-language/reference/built-in-functions/decision/isjson.md).

# IsJSON

Evaluates whether a string is in valid JSON (JavaScript Object Notation) data interchange format.

## Method Signature

```
IsJSON(var=[any])
```

### Arguments

| Argument | Type  | Required | Description                | Default |
| -------- | ----- | -------- | -------------------------- | ------- |
| `var`    | `any` | `true`   | The value to test for JSON |         |

## Examples

### isJSON Example

Returns true when the argument is a valid JSON value.

[Run Example](https://try.boxlang.io/?code=eJzLLPYK9vfTUFCKNtQx0jGOVVLQtOYCAD3kBNc%3D)

```java
isJSON( "[1,2,3]" );

```

Result: true

### Additional Examples

[Run Example](https://try.boxlang.io/?code=eJydj7FqwzAQhmf7KQ5NDmionBYKxUOTThlSirsFD6f0aASy3ZytGvfpKzkppK49NCAh8Yvv%2B08dm5aeXPmRgEVNNhOPzNgLCZ%2FImWk2TV0lIHZKpnJZCFjA4iHu%2FkC5qd4tQeVKTexR62ikULNoyx6eZETjGqPS5e3dfPEFDZ1pD9AQG7Tmizb583YkDFH%2B8372D%2Bpp%2BaquLWF1pb1lD82610zoI79fTfl%2F%2BW88gfRG3UtQl%2BvUHdqP3EMGR0fcb6nz%2F0ZEqbX2FcJ37A%2FIQ1m4%2BGwXR35FAoUMhxZxVMhztj9lbyGLi%2BmvvYSi0fhhhGGWb41ZwUw%3D)

```java
writeDump( label="Array", var=isJson( "[1,2,3]" ) );
writeDump( label="Single number value", var=isJson( 1 ) );
writeDump( label="String value", var=isJson( "susi12345" ) );
writeDump( label="String value with serializeJSON", var=isJson( JSONSerialize( "susi" ) ) );
writeDump( label="Boolean value with serializeJSON", var=isJson( JSONSerialize( true ) ) );
writeDump( label="CreateDateTime with serializeJSON", var=isJson( JSONSerialize( CreateDateTime( 2018, 1, 1, 1, 1, 1 ) ) ) );
qry = queryNew( "aaa,bbb", "varchar, varchar", [
	[
		"a",
		"b"
	],
	[
		"c",
		"d"
	]
] );
writeDump( label="Query", var=isJson( qry ) );

```

## Related

* [ArrayIsEmpty](/boxlang-language/reference/built-in-functions/decision/arrayisempty.md)
* [arrayIsEmpty](https://github.com/ortus-boxlang/boxlang-docs/tree/v1.x/boxlang-language/reference/built-in-functions/decision/arrayIsEmpty.md)
* [Attempt](/boxlang-language/reference/built-in-functions/decision/attempt.md)
* [IsArray](/boxlang-language/reference/built-in-functions/decision/isarray.md)
* [IsBinary](/boxlang-language/reference/built-in-functions/decision/isbinary.md)
* [IsBoolean](/boxlang-language/reference/built-in-functions/decision/isboolean.md)
* [IsBoxSet](/boxlang-language/reference/built-in-functions/decision/isboxset.md)
* [IsClosure](/boxlang-language/reference/built-in-functions/decision/isclosure.md)
* [IsCustomFunction](/boxlang-language/reference/built-in-functions/decision/iscustomfunction.md)
* [IsDate](/boxlang-language/reference/built-in-functions/decision/isdate.md)
* [IsDateObject](/boxlang-language/reference/built-in-functions/decision/isdateobject.md)
* [IsDebugMode](/boxlang-language/reference/built-in-functions/decision/isdebugmode.md)
* [IsDefined](/boxlang-language/reference/built-in-functions/decision/isdefined.md)
* [IsEmpty](/boxlang-language/reference/built-in-functions/decision/isempty.md)
* [IsFileObject](/boxlang-language/reference/built-in-functions/decision/isfileobject.md)
* [IsIPv6](/boxlang-language/reference/built-in-functions/decision/isipv6.md)
* [IsLeapYear](/boxlang-language/reference/built-in-functions/decision/isleapyear.md)
* [IsLocalHost](/boxlang-language/reference/built-in-functions/decision/islocalhost.md)
* [IsNull](/boxlang-language/reference/built-in-functions/decision/isnull.md)
* [IsNumeric](/boxlang-language/reference/built-in-functions/decision/isnumeric.md)
* [IsNumericDate](/boxlang-language/reference/built-in-functions/decision/isnumericdate.md)
* [IsObject](/boxlang-language/reference/built-in-functions/decision/isobject.md)
* [IsQuery](/boxlang-language/reference/built-in-functions/decision/isquery.md)
* [IsRange](/boxlang-language/reference/built-in-functions/decision/isrange.md)
* [IsSimpleValue](/boxlang-language/reference/built-in-functions/decision/issimplevalue.md)
* [IsStringBuilder](/boxlang-language/reference/built-in-functions/decision/isstringbuilder.md)
* [IsStruct](/boxlang-language/reference/built-in-functions/decision/isstruct.md)
* [IsValid](/boxlang-language/reference/built-in-functions/decision/isvalid.md)
* [IsXML](/boxlang-language/reference/built-in-functions/decision/isxml.md)
* [IsXmlAttribute](/boxlang-language/reference/built-in-functions/decision/isxmlattribute.md)
* [IsXMLDoc](/boxlang-language/reference/built-in-functions/decision/isxmldoc.md)
* [IsXMLElem](/boxlang-language/reference/built-in-functions/decision/isxmlelem.md)
* [IsXMLNode](/boxlang-language/reference/built-in-functions/decision/isxmlnode.md)
* [IsXMLRoot](/boxlang-language/reference/built-in-functions/decision/isxmlroot.md)
* [LSIsNumeric](/boxlang-language/reference/built-in-functions/decision/lsisnumeric.md)
* [structIsEmpty](/boxlang-language/reference/built-in-functions/decision/structisempty.md)


---

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